Here's how you can apply a color label to a file in OS X Mountain Lion by using the Get Info menu. 1. Select the file. 2. Press Command +I on your keyboard (or select File then Get Info from the file's menu on the menubar). 3. Look for the Label section under the General tab. 4. Click the color you want to use for your label.
For more, see the original article at the link below.
Use the Get Info window in Mac OS X | Daily Mac Tips